I had the same error with Windows 7, Tomcat 7.0, and JDK 1.6.0_31. I fixed it by changing the path to the JVM from C:\Program Files\Java\jre6\bin\server\jvm.dll to C:\Program Files\Java\jdk1.6.0_31\jre\bin\server\jvm.dll. To do that, run Tomcat7w.exe from the Tomcat bin directory, switch to the Java tab, and change the Java Virtual Machine entry.